This patent application claims priority to German Patent Application No. 100 60 218.5-14 filed Dec. 4, 2000.
The invention relates to a roll-hardening machine for crankshafts with hard-rolling tools which each have a hard-rolling roller head and a counter-support roller head that are each detachably attached to the ends of appropriate scissors arms by means of two clamping blocks wherein respectively a first of the two clamping blocks is positioned on the front surface of the end of the scissor arm and the second clamping block is located at a right angle to the first on the side surface of this same scissor arm on the tool side.
A roll-hardening machine for crankshafts of this type is known, for example, from EP 0 881 041 A2 by the same applicants. In particular the attachment of the hard-rolling tool is shown in FIGS. 2a, 2b, 2c and 3 of this European Patent Application. A single hard-rolling tool consists of a hard-rolling roller head, denoted by 66 in the European Patent Application, and a counter-support roller head, denoted by 74 in said Application. A hard-rolling head 66 and counter-support roller head 74 forming the hard-rolling tool are respectively attached to the ends 65 and 73 of the appropriate scissors arms 46 and 47. No details of the attachment are specified in the Application, although the aforementioned figures show clamping blocks by means of which the hard-rolling head 66 and the counter-support roller head 74 are respectively attached from two sides to a scissors arm 46 or 47 by screws. These are detachable fastenings which are accomplished by means of screwed joints since both the hard-rolling head 66 and the counter-support roller head 74 must be exchanged from one case to another. In order to replace the hard-rolling tool, the screwed joints of the relevant clamping blocks must be loosened before the hard-rolling roller head or the counter-support roller head can be removed. When clamping the hard-rolling tools, the screwed joints must be tightened again every time.
The loosening and re-tightening of the screwed joints is time-consuming, regardless of the fact that the hard-rolling tools are not always easily accessible in the hard-rolling machine. Changing the known hard-rolling tools accordingly lengthens the setting periods of the hard-rolling machine.
From said disadvantages it is the object of the present invention to substantially reduce the setting periods of the hard-rolling machine. At the same time, the hard-rolling tools should be attached to the hard-rolling machine in such a way that the hard-rolling force can be measured and the state of the hard-rolling rollers can be determined.
The first clamping block is supported on the front surface at the end of the respective scissors arm such that it can slide in the direction of the appropriate hard-rolling tool; the hard-rolling roller head is supported and moveably received by the second clamping block on the scissors arm, by having guide grooves on its front surfaces facing the scissors arm, in which prismatic blocks of the scissors arm engage; and the second clamping block for the counter-support roller head is supported such that it can move elastically in the clamping direction at its scissors arm.
This type of moveable attachment of the hard-rolling tools to the hard-rolling machine has a multitude of advantages. By incorporating grooves on the front surfaces of the hard-rolling roller head and counter-support roller head facing the scissors arms these two hard-rolling tools can be moveably supported in the hard-rolling machine. At the same time they can also be clamped and unclamped in a simple fashion in that the clamping blocks with which the hard-rolling tools are respectively attached at the end of the appropriate scissors arm are supported slidably in the direction of the hard-rolling tool. For the counter-support roller head the first clamping block is, for example, engaged and disengaged by means of an eccentric lever and for the hard-rolling roller head the first clamping block is automatically held in the locking position by means of a compression spring. Said first clamping block can then be moved out therefrom by means of a simple hand tool so that the hard-rolling roller head can be unclamped from the machine.
In addition to the clamping and unclamping of the hard-rolling tools in the hard-rolling machine being simplified, the movable bearing of the hard-rolling tools inside the machine also allows forces and states important for the problem-free operation of the hard-rolling machine to be determined. Thus, for example, it is possible to bring the hard-rolling roller head on the front surface facing the hard-rolling rollers in contact with piezoelectric sensors by means of which the appropriate hard-rolling force can be measured exactly. On the basis of these measured values it is then possible to regulate the hard-rolling force so that the crankshaft remains straight during hard rolling and thereafter exhibits no eccentricity. With the aid of another sensor which engages in one of the front surfaces of the hard-rolling roller head it is even possible to determine the state of the hard-rolling rollers. Here use is made of the fact that the guide roller which is placed inside the hard-rolling roller head and serves to guide the hard-rolling rollers, runs true irregularly when these are worn or ruptured. The regularity of the true running of the guide roller can be determined using projections or recesses at the edge of the guide roller in connection with the sensor which is constructed as a proximity switch. Irregularities here indicate wear or rupture of the hard-rolling rollers.
In order to avoid changing the hard-rolling tools for different crankshafts, there are provided index pins which engage from the hard-rolling roller head or counter-support roller head into holes located in the adjacent front surfaces of the scissors arms. This indexing ensures that in each case, only the hard-rolling tool provided for the appropriate type of crankshaft is installed in the hard-rolling machine.
The moveable support of the counter-support roller head has the advantage that the support rollers can conform to the respectively crankshaft bearings being hard-rolled with a high degree of uniformity.
Finally there are provided tool-changing tongs which can be attached one after the other on the hard-rolling roller head as well as on the counter-support roller head in order to change the appropriate hard-rolling tool can easily and without any risk to the machine tool setter. For using the tool-changing tongs, projections are provided in each case on the accessible front surfaces of the hard-rolling roller head and counter-support roller head to which the tool changing tongs can attach.